Folding of sheet-material blanks

ABSTRACT

A sheet-material blank is advanced in a path and from laterally of the path a folding member is advanced slowly towards and into engagement with the blank, whereupon it is accelerated beyond the path to the other side thereof. The deflecting member is then withdrawn and the deflected portions of the blank are engaged between two rollers which rotate in mutually opposite directions and the blank is thereby folded by engagement with these rollers through the nip of which it passes.

United States Patent [191 Hertrich et al.

[ FOLDING OF SHEET-MATERIAL BLANKS [75} Inventors: Klaus Hertrich,Goehrcnz; Horst Fenske, Leipzig, both of Germany [73] Assignee: VebPolygraph Leipzig Kombinat t'ur Polygraphische Maschinen undAusrustungen, Leipzig, Germany 22 Filed: 0a. 27, 1972 2 l] Appl. No:301,603

[52] US. Cl. 270/83 [5|] Int. Cl r B65h 45/18 [58] Field of Search270/6, 7, 83, 85, 80; 74/25 [56] References Cited UNITED STATES PATENTS1,867,909 7/1932 Dcligianes ct al. 270/67 1,960,682 5/1934 Sokolow ctal. i 270/67 2,837,013 6/l958 Pagcndarm 93/36.0l

3,l86,244 6/1965 Baker C! a]. 74/40 [451 Sept. 9, 1975 FOREIGN PATENTSOR APPLICATIONS 1,238,490 4/1967 Germany 270/83 l,l08,498 6/1961 Germany270/83 Primary Examiner-Robert W. Michell Assistanl Examiner-A. HeinzAttorney, Agent, or Firm-Michael S, Striker 5 7 ABSTRACT Asheet-material blank is advanced in a path and from laterally of thepath a folding member is advanced slowly towards and into engagementwith the blank, whereupon it is accelerated beyond the path to the otherside thereof. The deflecting member is then withdrawn and the deflectedportions of the blank are engaged between two rollers which rotate inmutually opposite directions and the blank is thereby folded byengagement with these rollers through the nip of which it passes.

4 Claims, 3 Drawing Figures sum 1 0f 2 FIG.2

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sumzngz FIG.3

FOLDING OF SHEET-MATERIAL BLANKS BACKGROUND OF THE INVENTION The presentinvention relates to the folding of sheetmaterial blanks and moreparticularly to a method and an apparatus for effecting such folding.

Sheet-material blanks must frequently be folded. for instance to form asignature in a book, brochure or the like. Such folding is usuallycarried out by means of a longitudinal or transverse folding deviceassociated with so-called rotary folders of the type used in variousrotary printing machines which use sheet material. As a rule, thesefolding devices use a conically or analogously convergent guide in whichthe sheet material blank is made to advance whereby it becomesprogressively folded. Another approach known from the art is to usetransverse folding cylinders. In some instances, where the fold must becarried out with particular accuracy, so-called knife-folders areemployed. These knives" are folding elements which are guided to performa movement during which they engage the respective sheet material blankand fold it. It is known to guide the knife in a straighbline guide orto articulate it to a swingable arm.

The problem with these latter types of folders is the drive for themovement which is to be performed by the knife, particularly if theknife is required to form a fold on a large-format sheet-material blank.This means that the knife must pass through a relatively sig nificantstroke, and of course in modern equipment the high-speed operation ofthe machines necessitates that the number of strokes be correspondinglygreat. This means that a cam control of the knife movement, theinherently ideal way of controlling the movement, is no longer possible.It has already been attempted to effect the control by means ofpneumatic cylinder and piston units, and alternately by means ofelectromagnetic units. These last two types of drive arrangements havethe disadvantage that the number of strokes which is required in modernmachines per unit of time, cannot be achieved. Moreover, the drivesaccelerate the knife or deflecting element in such a manner that itengages the respective sheetmaterial blank in shock-like manner, adisadvantage in terms of the accuracy of folding which can be obtained.

Some improvement was obtained in this field by using straight-linearticulated crank linkages. Such crank linkages are driven and theoutput member of the linkage is associated with the knife which it thenmoves in a straight line. The difficulty with these arrangements is thatthe speed of movement of the last element. that is here the knife,decreases significantly long before the knife reaches the end of itsworking stroke. This means that the sheet-material blank engaged by theknife receives only a relatively brief but very strong impulsedeflecting it out of the path in which it travels, but is not positivelyguided subsequently because of the progressive retardation in the speedof advancement of the knife. Thus, the deflected portions of the sheetmaterial blank will slide more or less freely under the impulseinitially imparted to them by the knife, in the direction in which theyhave been deflected by the knife, before they are engaged by the foldingrollers which then complete the folding operation. In many instances,however, the sheet-material blanks have al ready previously been foldedby means of control folding guides or other devices, so that they are ofV- shaped configuration, that is they are already bi-folded in onedirection. This means that at the opposite sides of the sheet-materialblank, that is at the opposite lat eral edges thereof, differentstiffness and friction coefficients exist. This, in turn, means that assoon as the blank is no longer positively guided by contact with theknife, it will tend to shift its configuration and position anddepending upon the mass and the speed of the initial impulse imparted toit. it will reach the folding rollers at some angle of inclination.This, as is well known to those conversant with the art, results invarious types of difficulties.

SUMMARY OF THE INVENTION It is, accordingly, an object of the presentinvention to avoid the disadvantages of the prior art.

More particularly it is an object of the present invention to provide animproved folding apparatus for folding of sheet-material blanks, whichis not possessed of the aforementioned disadvantages.

Another object of the invention is to provide an improved method ofeffecting the folding of sheet material blanks.

ln pursuance of these objects, and of others which will become apparenthereafter, one feature of the invention resides in guiding asheet-material blank in a predetermined path, and advancing a deflectingelement (e.g., a folding knife) at relatively slow speed from one sideof the path toward and into engagement with the blank Thcreupon, thedeflecting element is accelerated and simultaneously advanced togetherwith portions of the blank out of the path and to the opposite side ofthe latter, where such portions can be engaged by the folding rollers.According to the invention the acceleration of the deflecting elementassures that it will always be in positive guiding engagement with thedeflected portions of the sheet-material blank so that the disadvantagesof the prior art cannot occur.

The apparatus for carrying out the novel method is capable of producingat high speed and can therefore be employed to economic advantage. Theinvention is applicable both to transverse folders and to longitudinalfolders, that is apparatuses which effect transverse or longitudinalfolding of a sheet material blank. It assures that the deflectingelement engages the sheetmaterial blank at low speed, rather than toimpart a strong impulse thereto. Once the blank has been engaged, thedeflecting element is accelerated together with the blank and the latteris thus being positively guided by continued engagement with thedeflecting element until the deflected portions of the sheet materialblank have reached a position in which they can be engaged by thefolding rollers.

According to a currently preferred embodiment of the invention weutilize an articulated crank linkage which drives the deflecting elementin a straight-line path, and whose movement is in turn controlled by socalled antiparallel crank linkages. The output member of the antiparallel crank linkages is at one and the same time also the inputmember of the straight line crank linkage arrangement. However, it isalso possible to use, in place of the anti-parallel crank linkages,elliptically configurated Wheels.

The novel features which are considered as charac teristic for theinvention are set forth in particular i the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation,

together with additional objects and advantages thereof, will be bestunderstood from the following description of specific embodiments whenread in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a somewhat diagrammatic sideview illustrating one embodiment of the invention;

FIG. 2 is a graph comparing the characteristics of movement of thedeflecting element in an apparatus according to the present inventionand in accordance with the prior art; and

FIG. 3 is analogous to FIG. I but illustrating a further embodiment ofthe invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Discussing firstly theembodiment in FIG. 1 it will be seen that reference numeral 1 designatesa somewhat diagrammatically illustrated rotatable drive shaft 1 whichdrives a crank 2 which, together with a coupling element 3, a crank 4and a fixed element 5 constitutes a countermotion anti-parallel crankdrive in which during rotation of the crank 2 in one direction the crank4 connected thereto by the coupling element 3 rotates in the oppositedirection at rotational speeds different from those of the crank 2. Inaccordance with the present invention the crank 4 is in the outputelement of the anti-parallel crank drive, but at the same time is alsothe input or drive crank of the straight-line crank linkage arrangementwhich, in addition to the crank 4, has the coupling element 6, the gliderod 7 which carries at its front the deflecting element 9, and thestraight-line guide 8.

Reference numeral 11 identifies a guide having the illustrated slotwhich registers with the nip l4 and find between two folding rollers 13and 14 which rotate in mutually opposite directions as illustrated bythe associated arrows. The sheet-material blanks 10, of which one isshown, advances on this guide 11 in a predetermined path, defined by thesurface of the guide 11 which face upwardly in FIG. 1. They move acrossthe gap in the guide 11 and it will be understood that they havepreviously been severed from endless webs of sheet material, that theymay have been printed or otherwise processed, that they may have beenfolded longitudinally and/or transversely and that there may be morethan one of these blanks l 1 provided on the guide 11 in overlyingrelationship. In other words, it is possible to fold two or more of theblanks l0 simultaneously.

It is clear that when the element 9 moves from one side of the path (theupper side in FIG. 1) across the path to the other side (the lower sidein FIG. 1), it deflects the blank as illustrated through the slot in theguide 11. Depending upon the length of the stroke required to beperformed by the element 9, the coupling element 6 may be pivoted at apivot 15 or if maximum stroke length is required, at the pivot 16 whichin any case exists and connects the coupling element 3 with the crank 4.It is also possible, however, to provide an arrangement in which thepivot 15 can be shifted on the crank 4 in order to permit the strokelength to be varied if and as required.

If the arrangement uses only a single straight-line crank linkagearrangement, for instance that illustrated in FIG. 1 and comprising thecrank 4, the coupling ele ment 6, the rod 7 and the guide 8, as is knownfrom the prior art, then the element 9 will be undergoing onlyinsignificant acceleration at the time it contacts the blank 10 at pointA, (see FIG. 2), as indicated by the solid line 20 in FIG. 2. Theacceleration which the element 9 has at the time it contacts the blankIt) at point A,, is maintained over only a short period S, until thepoint E, is reached. FIG. 2 shows clearly that the speed of the element9 decreases quite rapidly in the direction towards the point E,, so thatthe deflected blank 10 is no longer being positively guided byengagement with the element 9 and will be able to move relatively freely(without guidance) in the direction towards the nip 14 (FIG. 1

Relatively expensive attempts have been made to overcome this problem inthe art, for instance to retard the blank 10 by brake or frictionrollers located above the guide 1 1, so as to prevent the free movementof the deflected portions of the blank, that is movement which iscontinued at the initial speed of deflection whereas the element 9 isprogressively retarded. Even this, however, has been of no help in theprior art and especially due to the fact that the blanks 10 have usuallyalready been previously folded one or more times, the problems occurwhich have been outlined above, as soon as the non-positively guidedblank is then engaged by rollers 12 and 13.

The present invention, however, avoids these difficulties. FIG. 2 showsthat during the working stroke of the element 9 there is obtained adistance-speedrelationship as is indicated by the broken line 21 in FIG.2. It will be noted that the element 9 engages the blank 10 at point Awith relatively low speed and that it then accelerates the blankincreasingly until it extends substantially beyond the guide ll; theacceleration of the element 9 and consequently of the blank 10 isterminated only when the nip 14 has almost been reached, that is it isterminated almost at point Ii where the working stroke of the element 9ends. This means that the difficulties inherent in the prior art havebeen avoided, because any undesired displacement of the blank 10 is nolonger possible because it has already been engaged by the rollers 13and 14 and is positively guided by them.

If, in accordance with the prior art, only a straightline crank linkagedrive is utilized, guidance of the blanks 10 can be effected only in theregion s, of FIG. 2, that is between the point of contact A, which isreached at almost maximum speed and the point E In contradistinctionthereto, the present invention makes it possible to positively guide theblank 10 over a substantially longer distance s extending between thecontact point A, which is reached at relatively low speed of the element9, and the point E which is almost coincident with the end of theworking stroke of the element 9. This means that at identical angularspeed of the respective crank drive and at better utilization of theoperating rhythm, an improvement of the folded blanks, that is thequality of the folds thereof, is obtained with the present invention.This is obtained by having the movement of the element 9, and thereforethe deflection of the blank 10, be continuous in accordance with thepresent invention and by guiding the blank 10 positively from the momentit is deflected out of its path until it is engaged by the rollers 12and I3 at the nip 14 thereof.

In FIG. 3 we have illustrated a further embodiment of the invention.Like reference numerals identify the same components as in theembodiment of FIG. 1. Here, however, we have illustrated that in placeof the anti-parallel cranks 2-5 it is possible to mount on the driveshaft 1 an elliptical wheel 17 which cooperates with an elliptical wheel19 of identical size and which is mounted for rotation on a shaft 18.The spacing of the axis of the shaft 18 from the axis of the shaft 1corresponds to the distance of the fixed points of articula tion of themember 5 of the embodiment in FIG. 1. The coupling member 6 would thenhave to be articulated on the large elliptical axis of the wheel 19. Thedata given in FIG. 2 with respect to the operation of the embodiment ofFIG. 1, and the comparison with the prior art which is provided in FIG.2, hold identically true with respect to the embodiment of FIG. 3.

it will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofconstructions differing from the types described above.

While the invention has been illustrated and described as embodied in anapparatus for folding sheetmaterial blanks, it is not intended to belimited to the details shown, since various modifications and structuralchanges may be made without departing in any way from the spirit of thepresent invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can by applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended claims:

1. In an apparatus for folding sheet material blanks, a combinationcomprising guide means for guiding sheet material blanks substantiallyin a plane; articulated crank linkage means mounted to one side of saidplane and comprising a deflecting element guided for straight-linemovement in a direction transversely of said plane from a startingposition in which it is located in its entirety at said one side of saidplane to an operating position in which it extends with a portionthereof across said plane to the other side of the latter, whereby toengage and in part deflect the blank in said direction; and controlmeans associated with said linkage means and operative for transmittingmotion to said element in such a manner that the element moves from saidstarting position to said plane and travels at a relatively slow speedwhen reaching said plane and is thereupon accelerated to a higher speedwhile traveling from said plane toward said operating position, saidcontrol means comprising a pair of elliptically configurated turnablewheels having respective peripheries and being mounted for turningmovement about parallel axes located in such a manner that theperipheries of said wheels remain in engagement during turning of saidwheels about said axes.

2. A combination as defined in claim 1, wherein said linkage meanscomprises an elongated linkage member having spaced end portionsarticulated to said deflecting element and one of said ellipticalwheels, respectively.

3. A combination as defined in claim 1; and further comprising a pair oftransversely spaced folding rollers mounted at said other side of saidplane for rotation in opposite directions about axes extendingsubstantially parallel to said plane, said folding rollers defining between themselves a gap which is aligned in said direction with saiddeflecting element so that part of said blank that is deflected by saiddeflecting element enters said gap.

4. A combination as defined in claim 3, wherein said guide meanscomprises a guide support having a slot which registers in saiddirection with said deflecting element and said gap, respectively.

1. In an apparatus for folding sheet material blanks, a combinationcomprising guide means for guiding sheet material blanks substantiallyin a plane; articulated crank linkage means mounted to one side of saidplane and comprising a deflecting element guided for straight-linemovement in a direction transversely of said plane from a startingposition in which it is located in its entirety at said one side of saidplane to an operating position in which it extends with a portionthereof across said plane to the other side of the latter, whereby toengage and in part deflect the blank in said direction; and controlmeans associated with said linkage means and operative for transmittingmotion to said element in such a manner that the element moves from saidstarting position to said plane and travels at a relatively slow speedwhen reaching said plane and is thereupon accelerated to a higher speedwhile traveling from said plane toward said operating position, saidcontrol means comprising a pair of elliptically configurated turnablewheels having respective peripheries and being mounted for turningmovement about parallel axes located in such a manner that theperipheries of said wheels remain in engagement during turning of saidwheels about said axes.
 2. A combination as defined in claim 1, whereinsaid linkage means comprises an elongated linkage member having spacedend portions articulated to said deflecting element and one of saidelliptical wheels, respectively.
 3. A combination as defined in claim 1;and further comprising a pair of transversely spaced folding rollersmounted at said other side of said plane for rotation in oppositedirections about axes extending substantially parallel to said plane,said folding rollers defining between themselves a gap which is alignedin said direction with said deflecting element so that part of saidblank that is deflected by said deflecting element enters said gap.
 4. Acombination as defined in claim 3, wherein said guide means comprises aguide support having a slot which registers in said direction with saiddeflecting element and said gap, respectively.